Fosi V3 Mono thoughts ---
I have had the V3 Mono’s for about a week now and have been very impressed with the sound quality and overall presentation of the imaging and the sound stage of these smaller amps. In an earlier post I talked about some of the differences and similarities to the Fosi ZA3 amp. I will now go into some detail on the characteristics of the V3 Mono.
Build quality: seems on par with the other Fosi amps that I have reviewed and listened in the past. The case and the pc board are very similar to the V3 and ZA3 amp quality wise. The capacitors and the electrical parts are the same or of similar quality from my non-technical background. The one thing that I wish Fosi Audio would do differently is use higher quality binding posts on their amps. In the case of the V3 Mono hooking up some of my 14-gauge speaker banana plugs makes for a tight fit in the back of the unit. A little bigger case and more physical space would be nice.
Auto on feature. On the right power switch there is an on/off switch with a position for an “auto” mode. Instead of the trigger that the ZA3 has that needs a physical cable between the preamp and the amp, the V3 Mono uses the audio signal to turn on. Like an external sub-woofer turning on when it senses that there is sound being send to the unit. It works well and I like the feature. In auto mode the unit turns off after 10-15 minutes after the audio source is not detected.
Temperature of the V3 mono: I was surprised on how warm the V3 Mono gets in comparison to other FosI amps. When driven pretty hard the amp becomes warm to almost hot to the touch. I am not use to this in most class D amps that I have had in the past. Fosi has made a very good video that explains why this happens.
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In the video they mention that the Fosi V3 Mono operates normally at 37 degrees Celsius. That is about 100 degrees Fahrenheit. I ran the Fosi in my setup for four hours at about 80db peak levels and the temperature got as high as 110 degrees on the case which is pretty warm to the touch almost hot. Unit never shut down or sounded strained. This is just the way the amp works.
Sound stage and polarity of outputs: you can see that the polarity in the picture that the red and black speaker connections are reversed. Red goes to the negative (black) speaker connection and black wire goes to the positive (red) speaker connection. This was a concern to me thinking that the speakers would be out of phase and hurt the sound stage imaging of the amp. After a check with Fosi, this is the correct wiring. The soundstage and imaging are fantastic in my audio system so this is not an issue.
Next post will be on my findings on op amp rolling.View attachment Fosi-mono-V3-mono-3-web-low.jpg
I have had the V3 Mono’s for about a week now and have been very impressed with the sound quality and overall presentation of the imaging and the sound stage of these smaller amps. In an earlier post I talked about some of the differences and similarities to the Fosi ZA3 amp. I will now go into some detail on the characteristics of the V3 Mono.
Build quality: seems on par with the other Fosi amps that I have reviewed and listened in the past. The case and the pc board are very similar to the V3 and ZA3 amp quality wise. The capacitors and the electrical parts are the same or of similar quality from my non-technical background. The one thing that I wish Fosi Audio would do differently is use higher quality binding posts on their amps. In the case of the V3 Mono hooking up some of my 14-gauge speaker banana plugs makes for a tight fit in the back of the unit. A little bigger case and more physical space would be nice.
Auto on feature. On the right power switch there is an on/off switch with a position for an “auto” mode. Instead of the trigger that the ZA3 has that needs a physical cable between the preamp and the amp, the V3 Mono uses the audio signal to turn on. Like an external sub-woofer turning on when it senses that there is sound being send to the unit. It works well and I like the feature. In auto mode the unit turns off after 10-15 minutes after the audio source is not detected.
Temperature of the V3 mono: I was surprised on how warm the V3 Mono gets in comparison to other FosI amps. When driven pretty hard the amp becomes warm to almost hot to the touch. I am not use to this in most class D amps that I have had in the past. Fosi has made a very good video that explains why this happens.
In the video they mention that the Fosi V3 Mono operates normally at 37 degrees Celsius. That is about 100 degrees Fahrenheit. I ran the Fosi in my setup for four hours at about 80db peak levels and the temperature got as high as 110 degrees on the case which is pretty warm to the touch almost hot. Unit never shut down or sounded strained. This is just the way the amp works.
Sound stage and polarity of outputs: you can see that the polarity in the picture that the red and black speaker connections are reversed. Red goes to the negative (black) speaker connection and black wire goes to the positive (red) speaker connection. This was a concern to me thinking that the speakers would be out of phase and hurt the sound stage imaging of the amp. After a check with Fosi, this is the correct wiring. The soundstage and imaging are fantastic in my audio system so this is not an issue.
Next post will be on my findings on op amp rolling.View attachment Fosi-mono-V3-mono-3-web-low.jpg